This invention relates to comminutors having signigicant solid material content carried by a flowing liquid, such as sewage for example, in a channel or pipe. Although the prior art comminutors have been of both the fixed or rotatable cage variety, the present invention is concerned primarily with the stationary or fixed cage variety and its improvements are directed to such comminutors. In the prior art these comminutors have had fixed cages generally formed of a plurality of axially spaced apart sections forming slots for the passage of the sewage, such devices may also include stationary cutting and shredding bars, commonly referred to cutter bars connected thereto, the bars have teeth formed thereon which may be in axial alignment with corresponding sections of the slots formed in the fixed cage. Such comminutor may have further means mounted in close spaced relationship with the fixed cage and cutter bars for interengaging comminutor actions.
Comminutors of foregoing types are well known and described in the prior art, for example such as in U.S. Pat. No. 2,305,935, to George L. Thom, issued Dec. 22, 1942. In this device the comminution of material contained in sewage is accomplished by a slotted straining member, either stationary or rotary, which intercepts pieces of materials which are too large to pass through the strainer slots and having cutting teeth which cooperate with one or more notched cutting bars to cut, shear or tear intercepted solids into pieces small enough to pass through the slots. In operation comminution of the solid materials occurs on the concave side of the strainer where a plurality of cutting teeth are disposed in the path of travel of the notches in the cutting bar, either one or more spaced about the axis of rotation of such bar or bars, whereby pieces are cut, sheared or torn form the solids that are caught between the cutting bar or bars and the cutting teeth.
U.S. Pat. No. 2,389,306, to Walter H. Green, issued Nov. 20, 1945 discloses in its preferred embodiment, a fixed semi-cylindrical grid forming a plurality of horizontal slots extending circumferentially to the grid having a plurality of rotatable circular discs having cutting teeth on the peripherie's of the discs by extending through the slots of the grid and a vertical cutter bar set into the wall of the conduit extending vertically along the periphery of the rotatable discs. In operation larger solids in the sewage are first caught or held by the upstream segments of the rotating plate which extend outwardly beyond the bars of the fixed grid, and will be nibbled by the rotating teeth or washed or carried over to the cutter bar. Thus such solids are caught between the cutting teeth and the cutting bar and small portions are punched through the cutter bar and into the down stream flow of sewage.
U.S. Pat. No. 2,594,785, to Herbert J. Meeker, issued Apr. 29, 1952, discloses a comminutor having a vertical stationary semi-cylindrical bar cage having a plurality of screening openings therein, further having one or more internal oscillating cutter arms together with means for oscillating the cutter arms backwards and forward over the concave surface of the cage. Each cutter arm carries shredding teeth which cooperate with shredding teeth removably carried by the bar cage to cut and shred collected screening openings in the semi-cylindrical bar cage. The cutter bar attached to the oscillating cutter arm or arms extends vertically across the inner concave surface of the semi-cylindrical cage at an acute angle such that the desired shearing action occurs advantageously.